Cells and tissues transmit various chemical and physical signals. These are response to an extracellular stimulus. All the cellular responses include molecular information as for intracellular biological processes. However, most of cellular signals are very weak and not easily detected with conventional analytical methods. In order to detect cellular signals, two types of tactics to monitor cellular signal under cell culture condition has been studied. First one is the molecular designing of "polymer metal polymer (PMP) complex" as molecular transducer for cellular nitric oxide sensor. The PMP complex is designed and synthesized on the basis of novel ideas on molecular designing. The PMP complex possesses both specific catalytic function and molecular transduceability. The multiproperties are given by peculiar coordinative self-assembled structure that is composed with two (or more) different polymers and metal ion(s). In the present case, PMP complex is designed for cellular NO detection. The PMP complex coated electrode can determine NO concentration from 100 nM to 100 mM in aqueous solution by amperometric measurement. Next one is a genetical construction of postsynapse model cell for an evaluation of extracellular neural transmitter. Postsynaptic function is presented by channel gate receptor on postsynaptic membrane. In the present study, cloned glutamic acid channel gate receptor (GluR-D) gene is transformed into insect cell Sf-9. Sf-9 is easy to cultivate and is able to express GluR-D on its cell surface as same as postsynaptic membrane. Its function can be monitored by outer cell potential. Both of tactics is successfully performed and is applicatable cultured cell-based assay on pharmaceutical screening and chemical safety proofing. (C) 2004 Elsevier B.V. All rights reserved.